The present invention relates to a micro fluid chip that leads liquids supplied from a plurality of liquid supply ports, respectively, to a minute flow passage, performs mixing and reaction (chemical reaction) of the liquids in the minute flow passage, and gets a processed liquid from a liquid discharge port.
A micro fluid chip is an apparatus that supplies a plurality of liquids to a minute flow passage having a width of and a depth of several μm to several hundreds μm and performs mixing and reaction of the liquids in the minute flow passage on the basis of the spontaneous behavior of molecules and particles, which constitute the liquids.
That is, the Reynolds number of liquids amounts to several hundreds or less in a minute flow passage provided in a micro fluid chip, and thus laminar flow becomes dominant unlike conventional reaction apparatuses, in which turbulent flow is dominant. Mixing/reaction of liquids under the domination of laminar flow is mainly caused by molecular diffusion at contact interfaces of the respective liquids, and the speed of molecular diffusion is prescribed by a thickness (a distance, over which different kinds of liquids should diffuse until they get uniform in concentration, =diffusion length) of the liquids in a direction of diffusion.
Many of conventional micro fluid chips is intended for analysis of liquids, and mixing/reaction of liquids at flow rate of several μl/min to several tens μl/min is performed in a minute flow passage having a small width (=short diffusion length) of several hundreds μm or less.
Concretely, micro fluid chips are known as disclosed in JP-A-2003-1077, in which a plurality of liquids, respectively, are divided into a multiplicity of laminar flows, and the laminar flows are arranged alternately to form a laminate flow, in which a ratio of contact areas of the respective liquids to a total volume of the liquids is increased, thus enabling mixing of liquids in high efficiency, and micro fluid chips are known as disclosed in JP-A-2002-346355, in which liquids are arranged in thin filmy flows, which are laminated perpendicularly to a flow direction, and mixing of liquids is performed by that agitating flow, which is generated by intermittently constricting the laminated flows.
With the prior art described above, micro fluid chips are designed on the assumption that small quantities of liquids in the order of several tens μl/min are analyzed, and when liquids are caused to flow at flow rate of the order of several tens ml/min for the purpose of mixing/reaction of the liquids, flow passages are too minute and so internal pressure loss becomes excessive to make flow at a desired flow rate impossible, so that an increase in throughput cannot be expected. Also, when liquids pass through minute flow passages at high speed, diffusion becomes insufficient to get expected mixing/reaction.
In order to achieve an increase in throughput and to get sure mixing/reaction, there is a need for parallel processing with the use of a plurality of micro fluid chips called numbering-up, so that a whole apparatus is made large in size.
Pressure loss in a minute flow passage in a micro fluid chip is greatly affected by the viscosity of a liquid. This is because a ratio of a circumference of a cross section to a cross sectional area of a flow passage is high and friction loss due to the viscosity is great at wall surfaces of the flow passage. Therefore, when a high-viscosity liquid is supplied to a micro fluid chip, stagnation and accumulation due to pressure loss are generated near wall surfaces, so that it becomes difficult to correctly feed the liquid.
In particular, in case of supplying a low-viscosity liquid and a high-viscosity liquid to give rise to mixing and reaction, a difference in pressure loss between the low-viscosity liquid and the high-viscosity liquid is generated, so that even when the low-viscosity liquid flows through a minute flow passage relatively smoothly, the high-viscosity liquid becomes stagnant. Accordingly, even when liquids are initially supplied at a desired ratio, a difference in flow rate is generated while the liquids flow through the minute flow passage, and one of the liquids becomes smaller in quantity than the other of the liquids, so that mixing at a desired ratio cannot be achieved when mixing should be done, and yield is decreased when reaction should be done. Then, the high-viscosity liquid becomes gradually stagnant in the minute flow passage to occupy a major part of the flow passage, so that desired mixing and reaction cannot be achieved.